I also got bitten by the "FC11 packages 'newer' than FC12" hickup,
and

while going through the yum remove/add maneuver I pondered:
- is there ever a time when, while upgrading from Fedora n to Fedora
n+1 I would expect a package .fcn to be kept instead of getting
the .fcn+1 instance ?
My answer was: no
So I wondered if there would be a simple way to make this happen
regardless of whether a maintainer blunders and gets things slightly
out of sync between the 2 or 3 current Fedora releases.

To me, this is the wrong fix. The problem here isn't RPM's version
comparison logic, which is perfectly sound. Instead of nerfing up RPM
comparisons, which are already full of enough hidden mines, we should
just improve Fedora's package versioning conventions so this doesn't
happen, or at least happens less often.

We should just use release epochs, people might hate them for whatever
reasons, but they would easily prevent such issues from happing.

Which sounds great until 3.0.1 goes out on f11 while 2.5 is out on
f12. Really don't want to see that "upgrade" happen.